In a semiconductor device represented by a silicon semiconductor, a miniaturization and a higher integration have been progressing in response to market needs such as higher performance and compact sizing. In accordance with the miniaturization and higher integration, as a metal for forming a fine wiring pattern, copper is mainly used due to having low wiring resistance. As a barrier layer to such a copper wiring, there has been known a metal layer (metal film) composed of a metallic titanium, a metal layer (metal film) composed of a metallic tungsten, an alloy layer (alloy film) of these metals, or the like.
In a formation process of a metal wiring, it is necessary to etch a metal composing such a barrier layer, and as an etching solution for etching these metals, an acidic etching solution, such as, for example, a mixed solution of hydrofluoric acid and hydrogen peroxide, a mixed solution of phosphoric acid and hydrogen peroxide, has been used conventionally.
However, since decomposition of hydrogen peroxide is promoted by a metal, such as, for example, copper, silver or gold, an etching solution containing the hydrogen peroxide has been known to have problems of a short solution life-time, and necessity of suitable control of concentration of hydrogen peroxide in the etching solution, and the like.
In addition, an etching solution containing hydrogen peroxide has been known to have problems of oxidation of the surface of the copper wiring, corrosion of the metal wiring such as a copper wiring, other than the problem of decomposition of hydrogen peroxide.
As an etching solution or an etching agent focused on such problems, there have been known conventionally, for example, an etching solution composed of specific amount of hydrogen peroxide and specific amount of a phosphate salt, for etching TiW (for example, PATENT LITERATURE 1); an etching agent composed of a solution containing hydrogen peroxide and a chelating agent, for a Ti-based film on a semiconductor substrate (for example, PATENT LITERATURE 2); a surface preparation agent composed of specific amount of hydrogen peroxide and specific amount of a phosphonic acid-based compound (for example, PATENT LITERATURE 3); an etching solution for etching tungsten and/or titanium-tungsten alloy, characterized by containing at least hydrogen peroxide water and an alkali component, and being a pH of 7 or lower, under presence of a metal having good electrical conductivity for a wiring or an electrode (for example, PATENT LITERATURE 4); an etching agent, which is an aqueous solution of an acidic region having a pH of 3.0 to 7.0, characterized by containing hydrogen peroxide, an alkali metal ion and an anticorrosive (for example, PATENT LITERATURE 5); an etching agent, which is an aqueous solution of an alkali region having a pH of over 7.0 to 8.0, characterized by containing hydrogen peroxide and an alkali metal ion from a supply source of a caustic alkali (for example, PATENT LITERATURE 5); an etching solution for a titanium or a titanium alloy film, which is the etching solution for etching the titanium or the titanium alloy under presence of a metal which should not be etched, and is an aqueous solution composed of specific amount of hydrogen peroxide, specific amount of phosphoric acid, specific amount of a phosphonic acid-based compound and ammonia (for example, PATENT LITERATURE 6); an etching agent for a semiconductor substrate, composed of a solution containing at least hydrogen peroxide, a phosphonic acid-based chelating agent having a hydroxyl group and a basic compound, and an anticorrosive and/or two or more kinds of anion species not having oxidation power, other than specific amount of the phosphonic acid-based chelating agent having a hydroxyl group (for example, PATENT LITERATURE 7); and the like.